Field of the Disclosure
The invention relates to a technique for allowing a timing generation logic to adapt to an abnormal power supply cutoff, an undesired reset instruction and the like which take place in the course of drive control and for example, a technique useful in application to a liquid crystal driver which pet forms an abnormal shutdown process.
Description of the Related Art
To stabilize a restart process after power supply recovery by means of an exceptional process different from a normal shutdown sequence with undesired power supply cutoff caused is necessary for not only a cooler as disclosed by the Japanese Unexamined Patent Publication No. JP-A-5-107837, but also many devices.
For instance, in case that an undesired power supply cutoff takes place owing to battery falling or the like during display driving in a liquid crystal driver operable to control, in display, a liquid crystal display panel incorporated in e.g. a personal digital assistant using a battery power supply, the liquid crystal display panel is in danger of suffering the degradation of characteristics. This is because in such a case, the liquid crystal driver cannot go through a normal power supply cutoff sequence and thus, the timing control to the liquid crystal display panel becomes unstable, and the display operation is stopped with undesired voltages remaining applied to display pixels. To eliminate such a danger, an exceptional process may be adopted; in the exceptional process, the polarities or timing signals to be supplied to the liquid crystal display panel are fixed to predetermined levels by use of a remaining capacity of the power supply at occurrence of the undesired power supply cutoff.
Now, it is noted that such an exceptional process is disclosed by JP-A-5-107837.